Oxidative hair dye colorants are essential elements in hair dyeing preparations for the permanent dyeing of human hair. The hair dyeing process is achieved, in general, by the reaction of certain primary intermediates with certain coupling compounds in the presence of a suitable oxidizing agent or compound, for example, hydrogen peroxide.
When oxidation dyes, such as those comprising primary dye intermediates and couplers, are used in the dyeing of human hair, the procedure typically involves the use of a two-part system. In general, one part can be a lotion, gel or cream formulation, which contains a variety of ingredients, including oxidation dye precursors (i.e., primary intermediates and coupling agents). The other part is a developer formulation containing a suitable oxidizing agent, e.g., hydrogen peroxide. Immediately prior to application to the hair, the two parts are mixed to form a thickened liquid solution, for example, a lotion, cream, or gel. As a consequence of the oxidizing properties of the oxidizing agent, some of the natural melanin pigment of the hair may be bleached. The oxidation dye precursors in the thickened solution (e.g., lotion or gel) penetrate into the hair, couple and are oxidized to produce the desired color. Such systems generally contain a proportion of organic solvents and surfactants and contain relatively high levels of dye precursors to produce the desired color.
In order for procedures using permanent oxidative dyes to work properly, a number of parameters and conditions are important to consider in the use of these dyes in admixture with couplers in hair color preparations for human hair. Among these are the final color and color intensity that are produced after application to the subject's hair; the wash fastness and the light fastness of the resulting dye; the resistance of the dye to perspiration; the type of hair being dyed, e.g., virgin hair or waved hair; the resistance of the dye to various hair treatments, such as permanent wave, straightening, shampooing, conditioning and rubbing. In addition, the dye must have virtually no allergenicity or dermal or systemic toxicity. Ideally, the dye product is also economical and must remain stable against the above-mentioned external influences and against chemical agents for a suitable period of time after application to the hair, for example, for at least four to six weeks, and to insure a reasonable shelf life.
The use of alkyl quaternary amines as conditioning agents in hair dye formulations has been known in the art for approximately twenty years. More recently, the use of polyquaternium compounds has provided durable conditioning properties to hair color formulations.
Highly aqueous bases as media for dyeing hair have been employed in the art (U.S. Pat. No. 4,776,855 and RE 33786). Thickening in a high aqueous base has been accomplished by adding a polyacrylic acid derivative to the peroxide developer. As a consequence, the polyacrylic acid derivative forms an insoluble mixture at the acid pH of the developer. When mixed with the alkaline dye formulation, the polyacrylic acid becomes neutralized, which leads to thickening.
Although such aqueous bases have been described for use in a conditioning hair color product (U.S. Pat. Nos. 5,376,146 and 5,393,305), there is a partial incompatibility between the conditioning agents and the polyacrylic acids. Such an incompatibility results in disadvantages to the use of polyacrylic acid derivatives combined with cationic conditioning agents, for example, quaternary amines or polymers. Specifically, some of the anionic polyacrylic acid complexes with the cationic quaternary amine or polymer, thus resulting in inefficient thickening and loss of conditioning effect.
The present invention solves the above-mentioned incompatibility problem by the use of particular nonionic polymers for thickening the two-part dye composition in combination with one or more cationic conditioning agents. The nonionic polymers will not complex with the conditioning agents, thereby resulting in more efficient thickening and conditioning of the product. These polymers, which are not known to have a conditioning effect on their own, have been newly-discovered by the present inventors to surprisingly act to enhance the conditioning effect of other conditioning agents which may be present in the product. The net result of the present invention is a hair color composition with excellent rheology and superior conditioning properties and benefits for two-part oxidative hair dye systems.